In recent years, attention is attracted to automobiles in which environment is considered, such as a hybrid vehicle (also called “HEV”), an electric vehicle (also called “EV”), and a fuel cell vehicle. Lately, there is a hybrid vehicle (also called “PHEV”) on which a charger is mounted. Meanwhile, laws and regulations are being prepared at home and abroad.
When a charger is mounted on a vehicle together with a battery, a circuit configuration is such that an output terminal of the charger is directly connected to a terminal of the battery for reasons such as simplification of a circuit and reduction of an electric power loss. Thus, in a state where the electric power of the battery is in use, such as during traveling of the vehicle, a high voltage is applied to an output section being a DC side of the charger. Since a high voltage is applied to a charger during traveling of a vehicle as described above, a place on which the charger is mounted is required to be a part where predetermined protection can be attained in case of occurrence of an accident. On the other hand, the charger has an insulation structure thereinside, and the electric power does not flow near an external connection terminal of a charging port being an input side, even in a state where the electric power of the battery is in use.
In Patent Literature 1 described later, it is disclosed to provide a relay for cutting off an on-vehicle charger from a high-voltage circuit.